
(from the article `small arm`) ...the Smith & Wesson patent expired in 1872, a host of new revolver designs appeared in the United States and Europe. The most important innovations ...
Found on
http://www.britannica.com/eb/a-z/d/69

Pistols which cock the hammer and release it on one pull of the trigger. This usually requires a longer pull than is required for a single action.
Found on
http://www.encyclo.co.uk/local/20524

An action type, typical on handguns, where the hammer may be cocked manually prior to each shot, OR, one may pull the trigger through a long throw which cocks the hammer (and in the case of a revolver, advances the cylinder) and fires the revolver in one complete motion. Photo
Found on
http://www.hallowellco.com/abbrevia.htm

when both fencers choose exactly the same moment to make an offensive action
Found on
http://www.hpfc.org.uk/glossary.htm

Double-action is a classification of firearms in which squeezing the trigger first causes the hammer to be raised and cocked and - in the case of a revolver - the cylinder rotated before the hammer is then released and the shot discharged, all within a single squeeze of the trigger. This differs to single-action in that the firer does not need to s...
Found on
http://www.probertencyclopaedia.com/browse/FD.HTM

when both fencers choose exactly the same moment to make an offensive action
Found on
https://www.encyclo.co.uk/local/20776

(of a firearm) requiring only one pull of the trigger to cock and fire it.
Found on
https://www.infoplease.com/dictionary/double-action
No exact match found.